Sodium nitrilotriacetate and processes for producing same

ABSTRACT

THIS INVENTION RELATES TO A DETERGENT ADDITIVE CONTAINING SODIUM NITRILOTRIACETATE PREPARED BY SPRAY DRYING AND WHICH MAY BE POST ADDED TO DRY DETERGENT FORMULATIONS.

United States Patent O 3,717,589 SODIUM NITRILOTRIACETATE AND PROCESSES FOR PRODUCING SAME William A. Feiler, Harold E. Feierstein, and Chung Yu Shen, St. Louis, Mo., and Norman Earl Stahlheber, Columbia, 111., assiguors to Monsanto Company, St. Louis, M0. N Drawing. Filed Sept. 17, 1970, Ser. No. 73,200

Int. Cl. Clld 3/066 US. Cl. 252-523 8 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a detergent additive containing sodium nitrilotriacetate prepared by spray drying and which may be post added to dry detergent formulations.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to spray dried detergent additives containing sodium nitrilotriacetate and to detergent formulations containing the same.

Description of the prior art One of the suggested ways to fight pollution of rivers and streams is to replace a portion of the phosphate in a detergent formulation with another builder such as trisodium nitrilotriacetate. A very convenient way to accomplish this with only minor adjustments to a detergent manufacture operation, would be by adding trisodium nitrilotriacetate to the detergent formulation after it has been completely processed to the dry state. However, commercially available trisodium nitrilotriacetate which is not spray dried is undesirable for addition in this manner for a number of reasons. The particles are generally in the form of very friable flat plates which tend to degrade in handling to particles of a size much smaller than that of the detergents which results in segregation after addition to typical detergent formulations. Additionally, the bulk density is generally heavier than that of most commercially available detergents. Also, the material tends to cake and tends not to be free flowing. It was found that when an aqueous slurry of trisodium nitrilotriacetate was spray dried, the bulk density was only slightly improved but the other undesirable physical properties were not improved. In particular, the frangibility of spray dried particles of trisodium nitrilotriacetate was poor and the particles degraded in normal handling.

Therefore, a detergent additive containing trisodium nitrilotriacetate which may be added to a detergent formulation with none of the above mentioned disadvantages would be an advancement in the art, particularly a detergent additive containing relatively coarse sized, nonfrangible, light density non-caking particles.

SUMMARY OF THE INVENTION In accordance with this invention, it has been found that a mixture of sodium nitrilotriacetate and another material (hereinafter defined) can be spray dried to produce a particulate detergent additive having certain physical properties (hereinafter set forth) which has none of the above mentioned disadvantages when admixed with a dry detergent formulation. By utilizing the detergent additive of this invention there is little or no segregation when it is admixed with a dried detergent formulation. Likewise, the particles are tough and will maintain their particle size after admixture. The product is free flowing and non-caking. The invention will be better understood from the following detailed description.

DETAILED DESCRIPTION OF THE INVENTION As mentioned before, the detergent additive of this invention is obtained by spray drying sodium nitrilotriacetate particularly disodium nitrilotriacetate (Na NTA), and/ or trisodium nitrilotriacetate (Na NTA) and another material. The terms Na NTA and Na NTA as used herein refer to the anhydrous form as well as the hydrate form. The other material is one of those in the following classes: crystalline modifiers, water dispersible polymers, film formers and pH modifiers.

Crystalline modifiers, as used herein refers to those materials which when spray dried along with sodium nitrilotriacetate prevent the sodium nitrilotriacetate crystals from growing into typical large plates which are very frangible. Illustrative of these materials include the carbonates, for example, the alkaline earth carbonates such as magnesium carbonates, the alkali metal carbonates such as sodium, potassium and ammonium carbonates, the chlorides, for example the alkaline earth chlorides and the alkali metal chlorides such as sodium chloride and potassium chloride, the phosphates, for example the orthophosphates, the condensed phosphates, the glassy phosphates, materials-such as sodium mono and diorthophosphates, sodium pyrophosphate, sodium tripolyphosphate, the so-called glassy phosphates containing 6 to 50 phosphorus atoms in the chains, and organophosphorus, the polyphosphates such as sodium or potassium 1, l-hydroxy ethylidine di-phosphonate and the amino polyphosphonates such as sodium or potassium amino trimethylene phosphonate. It is preferred to use the carbonates, the pyrophosphates, the tripolyphosphates and the glassy phosphates having 6 to 5 phosphorus atoms in the chain.

The amount of crystalline modifiers used in practicing this invention will depend to some extent on which crystalline material is being employed. As a general rule, however, an effective amount of the material to produce the detergent additive of this invention having the desired physical properties is at least 0.1% by weight based on the weight of sodium nitrilotriacetate. In most instances, it was found that an amount below 0.1% by weight does not produce a detergent additive having the desired physical properties. There is no upper limit on the amount of crystalline modifiers that may be utilized except as dictated by convenience and limitations of the spray tower equipment. For example, an amount up to about by weight or more based on the weight of sodium nitrilotriacetate may be utilized. However, in most instances, the amount used will be from about 1% by weight to about 25% by weight based on the weight of sodium nitrilotriacetate. Especially good results are obtained by using sodium carbonate and sodium tripolyphosphate in an amount of from about 2% by weight to about 10% by weight based on the weight of the sodium nitrilotriacetate. Of course, sodium hydroxide which is converted to sodium carbonate during spray drying can be used in suflicient amount to supply the sodium carbonate. The above mentioned materials may be added in the acid form in an amount to provide the salt of the acid in the final spray dried product. When used in the acid form, the material can serve both as a crystal modifier and a pH modifier hereinafter to be described. Another class of materials that can be used include water dispersible polymers having a viscosity of at least 5 centipoises (cps). Viscosity is determined by using a capillary viscometer on a 1% by weight sample at 20 C. Anionic, cationic or non-ionic polymers may be used. Anionic polymers include those containing only carboxylic acid, carboxylic acid anhydride, and carboxylic acid salt groups in a side chain. Cationic polymers that may be used include those containing an amine, a pyrrolidone or similar nitrogen containing nuclei. The non-ionic polymers that may be used include those containing in a side chain a carboxylic acid amide, pyrrolidone, a hydroxy, a hydroxy alkyl ether and/or a hydroxy group in a side chain. Mixtures of the foregoing may also be utilized.

An important class of synthetic organic polymers employed for the purpose of the invention consists of the synthetic polymeric water soluble anionic polymers having a viscosity of at least 5 cps. which are copolymers of compounds containing the group o O( JOH=CH-( J and at one other monolefinic monomer.

Another important class of synthetic polymers employed for the purpose of the invention consists of synthetic water soluble anionic polymers having a viscosity of at least cps. which are polymers of a compound containing the molecular group III (0 H2) :1 O

CHz-C 0 wherein n is an integer from zero to 1, inclusive.

The following water dispersible synthetic organic polymers illustrate the types of polymers which have been found to be effective for the practice of this invention: polyacrylate sodium salt, maleic anhydride-vinyl acetate, polyvinyl methylethermaleic anhydride, methacrylic acidmethacrylamide, polyacrylic acid, isopropenyl acetatemaleic anhydride sodium salt, itaconic acid-vinyl acetate, polyvinylpyridine-hydrochloride, and methylstyrene-maleic anhydride sodium salt, polyvinylpyrrolidone, styrenemaleic anhydride sodium salt, polyvinyl alcohol, polyvinylmethyether, methylmethacrylate-maleic anhydride so dium salt, polyvinyl acetate emulsion, acrylic acid styrene copolymer.

Where the copolymers are identified in terms of their monomeric constituents, it should be understood that the names applied to these copolymers refer to the molecular structure and are not limited to the polymers prepared by the copolymerization of specific monomers. In many cases, the identical copolymers can be prepared from other monomers and converted by subsequent chemical reaction to the desired copolymer.

Where the copolymer is derived from a polycarboxylic acid derivative and at least one other monomer copolymerizable therewith the polycarboxylic acid derivative may be maleic anhydride, methacryl and acrylic maleic acid, fumaric acid, aconitic acid, citraconic acid, the amides of these acids, the alkali metal (e.g., sodium, potassium and lithium), the alkaline earth metal (e.g., magnesium, calcium, barium and strontium), and ammonium salts of these acids, the partial alkyl esters (e.g., methyl, ethyl, propyl, isopropyl and butyl monoesters), the salts of said partial alkyl esters, and the substituted amides of these polycarboxylic acids. Where the hydrophilic maleic acid derivatives are used as one of the starting components to form the copolymer the hydrophobic comonomers may be, for example, styrene, alphamethylstyrene, vinyl toluene, chlorstyrenes, vinyl acetate, vinyl chloride, vinyl formate, vinyl alkyl ethers, alkyl acrylamides, alky methacrylamides, ethylene, propylene, and/or isobutylene.

Especially good results are obtained by using copolymers of ethylene and maleic anhydride, or acid or sodium salts thereof having a viscosity of from about 5 to about 8,500 cps. and these are preferred.

Some of the synthetic organic polymers and copolymers are more effective than others, the effectiveness being dependent in part upon the kind and number of said chain groupings in the particular polymer. In general, for effective results, the polymer shou d ha e a. Viscosity of at 4 least 5 cps. and ordinarily within the range of 10 to 10,000 cps.

Other water dispersible polymers include those derived from natural polymers such as alkaline casein, sodium carboxymethylcellulose.

As a general rule, the amount of polymer used to bring about the desired physical properties of the detergent additive will depend upon a number of things including the polymer employed. In most instances, an effective amount of the water dispersible polymer is at least 0.05% by weight based on the weight of sodium nitrilotriacetate. It has been found in most instances when less than 0.05 by weight is utilized that a detergent additive having the desired properties was not obtained. Generally, there is no limit on the amount of polymer that may be employed except as dictated by convenience and until a point is reached where liquid mixture of the polymer and sodium nitrilotriacetate becomes so viscous that it cannot be conveniently pumped. In most instances, a range from about 0.5 to about 2% by weight is preferable.

Another class of materials that may be used include film formers, i.e., those materials are capable of holding the sodium nitrilotriacetate crystals in a bead. Illustrative film formers include the Water soluble alkali metal silicates. Especially good results are obtained with sodium silicate having a Na O/SiO ratio of about 111.5 to 1:3.75. The natural waxes such as beeswax, carnauba, castor, and sperrnaceti and the synthetic waxes such as polyethylene glycols having a molecular weight of 1300 to 7500 may be used.

Other film formers that may be utilized include surfactants such as the non-ionic, anionic amphoteric and cationic surfactants or detergent actives. Anionic detergent actives which can be used in the detergent additives of this invention include both soap and non-soap detergent compounds. Examples of suitable soaps are the sodium, potassium, ammonium and alkylol-arnmonium salts of higher fatty acids (C -C Particularly useful are the sodium or potassium salts of the mixtures of fatty acids derived from coconut oil and tallow, i.e., sodium or potassium tallow and coconut soap. Examples of anionic organic non-soap detergent actives include the sulfated or sulfonated alkyl, aryl and alkylaryl hydrocarbons and alkali metal salts thereof, for example, sodium salts of long chain alkyl sulfates, sodium salts of alkyl naphthalene sulfonic acids, sodium salts of sulfonates, sodium salts of alkylbenzene sulfonic acids particularly those in which the alkyl group contains from 824 carbon atoms; sodium salts of sulfonated mineral oils, and sodium salts of sulfosuccinic acid esters such as sodium dioctyl sulfosuccinate. Advantageous anionic surfactants include the higher alkylaryl sulfonic acids and their alkali metal and alkaline earth metal salts such as, for example, sodium dodecyl benzene sulfonate, sodium tridecyl sulfonate, magnesium dodecyl benzene sulfonate, ammonium dodecyl toluene sulfonate, lithium pentadecyl benzene sulfonate, sodium dioctyl benzene sulfonate, disodium dodecyl benzene disulfonate, disodium di-isopropyl naphthalene disulfonate and the like as Well as the alkali metal salts of fatty alcohol esters of sulfuric and sulfonic acids, the alkali metal salts of alkylaryl (sulfothioic acid) ethers and the alkyl thiosulfuric acid, etc. Preferred anionic organic surface active agents are, as noted hereinbefore, sodium salts of alkylbenzene sulfonic acids and particularly preferred sodium salts of alkylbenzene sulfonic acids are those in which the alkyl group or radical contains 10 to 18, preferably 12 to 14, carbon atoms in a straight (i.e., unbranched) chain.

Nonionic surface active compounds can be broadly described as compounds which do not ionize but usually acquire hydrophilic characteristics from an oxygenated side chain, such as polyoxyethylene, while the hydrophobic part of the molecule may come from fatty acids, phenols, alcohols, amides or amines. Examples of nonionic surfactants include products formed by condensing one or more alkylene oxides of 2 to 4 carbon atoms, such as ethylene oxide or propylene oxide, preferably ethylene oxide alone or with other alkylene oxides, with a relatively hydrophobic compound such as a fatty alcohol, fatty acid, a fatty glyceride, a fatty amine, an aryl amine, a fatty mercaptan, tall oil, etc. Non-ionic surface active agents also include those products produced by condensing one or more relatively lower alkyl alcohol amines (such as methanolamine, ethanolamine, propanolamine, etc.) with a fatty acid such as aluric acid, cetyl acid, tall oil fatty acid, abietic acid, etc., to produce the corresponding amide.

Still other non-ionic surface active compounds include the amine oxides and phosphine oxides and preferably the unsymmetrical trialkyl amine oxides and phosphine oxides wherein two of the alkyl groups are lower alkyl groups (1 to 4 carbon atoms) and the other alkyl group is higher alkyl group (8 to 18 carbon atoms). Examples include dimethyldodecylamine oxide, dimethyl dodecylphosphine oxide, dimethyl tetradecyl amine oxide, dimethyltetradecylphosphine oxide, diethylhexadecylamine oxide, diethylhexadecylphosphine oxide and the like.

Particularly advantageous non-ionic surface active agents are condensation products of a hydrophobic compound having at least 1 active hydrogen atom and a lower alkylene oxide (for example, the condensation product of an aliphatic alcohol, preferably straight carbon chain mono-alkanols, containing from about 8 to about 18 carbon atoms) and from about 1 to about 100 mols of ethylene oxide per mol of the alcohol, or the condensation product of a diol containing from about 8 to about 18 carbon atoms in the alkyl group, preferably a straight chain alkyl group, and from about 1 to about 70 mols of ethylene oxide per mol of diol. Other advantageous non-ionic detergents include condensation products of ethylene oxide with a hydrophobic compound formed by condensing propylene oxide with propylene glycol.

Amphoteric surface active compounds can be broadly described as compounds which have both anionic and cationic groups in the same molecule. Such compounds may be grouped into classes corresponding to the nature of the anionic-forming group, which is usually carboxyl, sulfo or sulfato. Examples of such compounds include sodium N-coco beta amino propionate, sodium N-tallow beta amino dipropionate, sodium N-lauryl beta iminodipropionate and the like.

Other typical examples of these categories of the anionic, non-ionic, amphoteric and/ or zwitterionic surface active agents are described in Schwartz and Perry, Surface Active Agents Interscience Publishers, New York (1949); the Journal of American Oil Chemists Society, volume 34, No. 4, pages 170-216 (April 1957); and U.S. Pat. No. 3,308,067; all of which publications are incorporated herein by reference.

Especially good results are obtained by using the following materials which are preferred. A condensation product of 12 /2 moles of ethylene oxides with a linear alcohol having an average carbon chain length of about 11, a condensation of 50 moles of ethylene oxide with a linear alcohol having an average carbon chain length of 16.5, a condensation product of about 7 moles of ethylene oxide with a linear vicinal diol having an average carbon chain length of about 17, sodium lauryl sulfonate and sodium dodecyl benzene sulfonate.

The actual amount of film formers used will depend again on which particular film former is used. As a general rule, an effective amount of film former to achieve a detergent additive having the proper physical characteristics is at least 0.15% by weight based on the Weight of sodium nitrilotriacetate. It has been found that an amount lower than 0.15 produces a detergent additive that does not have the desired physical characteristics. There is no upper limit on the amount of film former that may be utilized except for the cationic, non-ionic, amphoteric and anionic surfactant. For example, an amount up to 50% by weight,

based on the Weight of sodium nitrilotriacetate may be utilized. In most instances, an amount of 0.5% to about 10% by weight is used. In the case of the cationic, nonionic, amphoteric and anionic surfactant, the upper limit is about 2% by weight based on the weight of sodium nitrilotriacetate. It is preferred to use from about 0.3% to 10% by weight (based on the weight of sodium nitrilotriacetate) of sodium silicate. It is preferred to use the above mentioned preferred non-ionic and anionic surfactants at about 1% by weight based on the weight of sodium nitrilotriacetate.

The fourth group of materials that may be utilized include the pH modifiers. These materials lower the pH of sodium nitrilotriacetate and in fact may convert some of the Na NTA to Na NTA. By doing this, a detergent additive having the above mentioned properties is obtained Examples of these materials include mineral acids such as sulfuric, hydrochloric, phosphonic; organophosphonic acids such as l-hydroxyl, ethylidene di-phosphonic; others such as sulfonic, dodecyl benzene, sulfonic, nitrilotriacetic acid; acid salts of the foregoing such as monoalkali metal phosphates, monoammonium, orthophosphates, sodium hydroxy ethylidene di-phosphonate and Na NTA. The actual amount of pH modifier utilized will depend upon its capacity of neutralizing the sodium nitrilotriacetate. In most instances, it will be preferable to decrease the pH to no lower than about 7. It is preferred that these materials be added to reduce the pH to about 9 to 10 at 20 C.

As mentioned before, the products of this invention are prepared by conventional spray drying techniques utilizing conventional spray drying equipment. Conventional temperatures are employed, for example from about 250 R, up to temperatures of about 1000 F., it is preferred to use from about 600 F. to about 900 F.

Liquid solution or slurry of sodium nitrilotriacetate are spray dried. It is preferred to use water. As a general rule, at least about 1% by weight of sodium nitrilotriacetate is present in the slurry or liquid. There is no upper limit on the amount except as limited by the pumping equipment, in fact, up to about 90% by weight of sodium nitrilotriacetate can be present. A suitable operable range is from about 30% by weight to about with about 50% to about 80% by weight based on the weight of sodium nitrilotriacetate being preferred.

The dry solid particle detergent additive obtained in accordance with this invention contains sodium nitrilotriacetate and an effective amount of a crystalline modifier, a water dispersible polymer, a film former or a pH modifier and may contain some water of crystallization or free water. It is preferred that sodium nitrilotriacetate be present in an amount of from 35% to 99% by weight based on the weight of the detergent additive, water in an amount of from 0 to 20% by weight based on the weight of the detergent additive with the balance being a crystalline modifier, a water dispersible polymer, a film former or a pH modifier. A preferred detergent additive contains Na NTA in an amount of from about 45-99% by weight, based on the weight of the detergent additive, Na NTA in an amount of from about 0 to 40% by weight based on the weight of the detergent additive, and a crystalline modifier, a water dispersible polymer, a film former or a pH modifier present in an amount of from about .1 to about 5% based on the weight of the Na NTA and water in an amount of about 0 to 10% based on the weight of the detergent additive. Essentially, all the particles are in the shape of spherical hollow beads, however, during spray drying some of the beads may become fractured and/or stick together and hence some of the particles may have an irregular shape. The detergent additive has a particle size such that 80% of the particles pass through the openings in a U.S. standard 14 mesh screen and 80% of the particles are larger than the holes of a U.S. standard 100 mesh screen. It is preferred that of the particles pass through the holes in a standard 10 mesh screen and 80% of the particles are larger than the openings in a U.S. standard 100 mesh screen.

The particles of the detergent additive are quite tough and have a frangibility value of less than 20 and preferably less than 10. By way of comparison, commercially available trisodium nitrilotriacetate has a frangibility value of 24. Frangibility is determined by placing a 100 gram sample on a shaker screen having openings smaller than the particles, and on which there are 325 grams rubber balls. After 15 minutes, the material that has passed through the screen is collected and weighed. This weight is the frangibility value. This test is more fully described in J. American Oil Chemist Society 510-516 1968). The bulk density of the detergent additive is from about 0.2 to about 0.8 and it is preferred that the bulk density be from about 0.35 to about 0.7. The material is free flowing and non-caking i.e., the material shows a lesser or greater tendency to cake than commercial available Na NTA.

Detergent compositions are prepared with the additives of this invention and anionic, non-ionic, cationic or amphoteric surfactant or mixtures thereof. Illustrative surfactants are set forth in col. 4, lines 3665 and col. 5, lines 44-46.

In addition to the foregoing surface active agents, in most instances other detergent ingredients will be used, such as the well-known phosphate detergent builders such as sodium tripolyphosphate, tetrasodium pyrophosphate, sodium and potassium sulfates and carbonates, sodium silicate, optical brighteners, corrosion inhibitors, anti redeposition agents, dyes and pigments. Generally, a formulated detergent base containing mixtures of the foregoing detergent ingredients and surface active agents will be prepared in a conventional manner such as by the conventional spray drying technique or by the preparation of a detergent base utilizing the reaction of sodium hydroxide and sodium trimetaphosphate to produce a material containing the normal detergent additives, asurface active agent and sodium tripolyphosphate hexahydrate as is disclosed in US. patent application Ser. No. 460,205 now U.S. Pat. 3,390,093.

The foregoing detergent bases will be blended with the composition of this invention to yield a detergent composition having from about 1% to about 55% by weight of nitrilotriacetates calculated on the basis of nitrilotriacetic acid. Preferred ranges are usually from about 3% to about 40% by weight calculated as nitrilotriacetic acid.

Typical illustrations of carrying out the invention are as follows:

ILLUSTRATION 1 A supply of commercial Na NTA is slurried and milled with water at 60 C. to produce an aqeuous suspension containing 70% by weight of Na NTA and sulficient sulfuric acid to give 2.66% sodium sulfate in the detergent additive. It is then pumped to a 8 in diameter 30 tall tower under a presure of 1800 lb./sq. in. and spray dried through an ST nozzle 42 with a 625 insert to yield a detergent additive of this invention. The inlet temperature is about 680 F. to about 750 F. and the outlet temperature is maintained at about 300 to 325 F.

By following the above procedure, a detergent additive having a particle size of about 90% +100 and 2% +14 U.S. standard mesh screen, a frangibility of 3.9 and a bulk density of about 0.66 was obtained.

In another run, a 40 by weight aqueous slurry of only Na NTA was spray dried according to the above procedure except that the inlet temperature was 610 15., the outlet temperature was 275 F., the pump pressure was 275 lb./sq. in., and nozzle was a whirl chamber number 2 with a number 2 insert. The spray dried Na NTA contained only a trace of +30 mesh and was 50% l' mesh. Bulk density was 0.5 and frangibility number was 38. This material was unsuitable as a detergent additive.

8 ILLUSTRATION 2 A slurry containing 70% by weight of Na NTA and 5% by weight, based on the weight of the Na NTA of sodium silicate having a Na O/SiO ratio of 1:2.0 pumped to an 80 high 20' in diameter tower under a pressure of 1500 lb./sq. in. and spray dried through SpraCo systems whirl chamber number 2 nozzles with a number 5 insert. The inlet temperature is about 800 F. and the outlet temperature is about 250 F.

Substantially similar results as above are obtained by substituting for the sodium silicate one of the following film formers: 1% by weight of sodium dodecyl benzene sulfonate, 1% by weight of the condensation product of a linear alcohol having an average chain length of 12 carbons with 12 /2 moles of ethylene oxide, and 1% by weight of the condensation product of a linear vicin'al diol having an average carbon chain length of 16.5 and 'an average of 7 moles of ethylene oxide.

ILLUSTRATION 3 A slurry containing 55 by weight of Na NTA and 3% by weight of sodium hydroxide, based on the weight of Na NTA is pumped to an 80' high 20' in diameter tower under a pressure of 1600 lb./ sq. in. and spray dried through a SpraCo systems whirl chamber number 2 nozzles with a number 5 insert. The inlet temperature is about 800 F. and the outlet temperature is about 250 F.

Substantially similar results are obtained by substituting for the sodium hydroxide one of the following (all percents by weight based on the weight of Na NTA), 10% by weight of sodium carbonate, 10% by weight of sodium tripolyphosphate, 5% by weight of sodium or potassium pyrophosphate, 5% by weight ammonium carbonate and 2% by weight of sodium 1, l-hydroxy ethylidene di-phosphonate.

About the same results are obtained as above when Na NTA is substituted in the same amount for Na NTA.

ILLUSTRATION 4 A slurry containing 65% by weight of Na NTA and 1% by weight of a copolymer of ethylene and maleic anhydride having a viscosity of about 8500 c.p.s. is pumped to an 80' high 20' in diameter tower under a pressure of 1900 lb./sq. in. and spray dried through an ST nozzle 42 with a 625 insert to yield a detergent additive of this invention. The inlet temperature is about 700 F. and the outlet tem perature is 300 F. to about 325 F.

Essentially similar results are obtained when one of the following is substituted for the copolymer, all percents by weights are based on the weight of Na NTA, 0.6% by weight of carboxy methylcellulose, 0.1% by weight of methylvinyl ether maleic 'anhydride copolymer having a viscosity of about 5000 c.p.s.

ILLUSTRATION 5 The pH of a slurry containing by weight of Na NT A is reduced to about 9, with orthophosphoric acid, it is then pumped under a pressure of 1000 lb./ sq. in. to an high 20' in diameter tower and spray dried through ST nozzles 42 with a number 625 insert to yield a detergent additive of this invention.

Substantially similar results are obtained by substituting for orthorphosphoric acid one of the following, sulfonic acid, citric acid, 1,1-hydroxy ethylidine diphosphonic acid, hydrochloric sulfuric acid, an acid salt of any of the foregoing and Na NTA.

ILLUSTRATION 6 To a slurry containing 2.5% of sodium hydroxide based on the weight of Na NTA is 70% by weight of Na NTA and 2% by weight of carboxy methylcellulose is added sodium bicarbonate to neutralize the excess alkalinity as sodium hydroxide and to form the equivalent of about 6.6% by weight of sodium carbonate based On the weight of Na NTA. Sufiicient water is added to reduce the apparent viscosity to 5000 centipoises. The slurry is pumped under a pressure of 1500 lb./ sq. in. to an 80' high 20 ft. in diameter tower and spray dried through ST nozzles 42 with a number 625 insert to yield a detergent additive of this invention. The inlet temperature is about 700 F. and the outlet temperature is about 325 F.

ILLUSTRATION 7 Thirty percent of the material obtained in Illustration 1 is blended to a dried detergent composition containing 10% alkyl benzene sulfonate, 10% sodium tripolyphosphate, 40% sodium sulfate, and 10% of various other ingredients.

Substantially similar results as above are obtained when one of the detergent additives prepared in Illustration 2-5 is substituted for the additive of Illustration 1.

What is claimed is:

1. A process for producing a detergent additive containmg at least 90% by weight sodium nitrilotriacetate, said process consisting essentially of spray drying an aqueous mixture consisting essentially of sodium nitrilotriacetate and an effective amount of a member selected from the group consisting of crystalline modifiers selected from the group consisting of alkali metal carbonates, alkali metal tripolyphosphates, alkali metal pyrophosphates and ammonium carbonates; water dispersible polymers, selected from the group consisting of ethylene maleic anhydride copolymers having a viscosity from 5 to about 8500 cps. and sodium carboxy methyl cellulose; film formers, se lected from the group consisting of water soluble alkali metal silicate; pH modifiers, selected from the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid, l-hydroxy ethylidene-l,l-diphosphonic acid and disodium nitrilotriacetic acid said effective amount being from 2% to of the weight of sodium nitrilotriacetate when said member is a crystalline modifier, from 0.5% to 2% of the weight of sodium nitrilotriacetate when said member is a water dispersible polymer or a film former and an amount sufiicient to reduce the pH of sodium nitrilotriacetate to about 9 when said member is a pH modifier, whereby a detergent additive consisting essentially of trisodium nitrilotriacetate and said member is produced having a bulk density of from about 0.2 to about 0.8 gram per cc., having a frangibility of less than 20, having essentially all particles in the shape of hollow spheres having a particle size such that 80% of the particles pass through the openings in 'a US. Standard 100 mesh screen and 80% 0f the particles are larger than the openings in a US. Standard 100 mesh screen, and said detergent additive being noncaking and free flowing.

2. A process according to claim 1 wherein said sodium nitrilotriacetate is Na NTA.

3. A process according to claim 2 wherein said member is selected from the group consisting of crystalline modifiers.

4. A process according to claim 2 wherein said member is a water dispersible polymer.

5. A process according to claim 2 wherein said member is a film former.

6. A process according to claim 2 wherein said member is a pH modifier.

7. A detergent additive consisting essentially of at least sodium nitrilotriacetonitrile and an effective amount of a member selected from the group consisting of crystalline modifiers, selected from the group consisting of alkali metal carbonates, alkali metal tripolyphosphates, alkali metal pyrophosphates and ammonium carbonates; water dispersible polymers, selected from the group consisting of ethylene maleic anhydride copolymers having a viscosity from 5 to about 8500 cps. and sodium carboxy methyl cellulose; film formers, selected from the group consisting of water soluble alkali metal silicate; pH modifiers, selected from the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid, l-hydroxy ethylidene-l,ldiphosphonic acid and disodium nitrilotriacetic acid, said efifective amount being from 2% to 10% of the weight of sodium nitrilotriacetate when said member is a crystalline modifier, from 0.5% to 2% of the weight of sodium nitrilotriacetate when said member is a water dispersible polymer or a film former and an amount sufficient to reduce the pH of sodium nitrilotriacetate to about 9 when said member is a pH modifier, essentially all particles having a shape in the form of spherical hollow beads, said additive having a particle size such that 80% of the particles pass through the openings in a US. Standard 14 mesh screen and 80% of the particles are larger than the openings in a US. Standard mesh screen, having a frangibility value less than 20, a bulk density of about 0.2 to about 0.8, and being noncaking and free flowing.

8. A detergent additive according to claim 7 wherein said sodium nitrilotriacetate is Na NTA.

References Cited UNITED STATES PATENTS MAYER WEINBLATT, Primary Examiner US. Cl. X.R. 

